music directors failed

1) Mohabbat zindabad from mugal-e-azam ----- rafi switch from high notes to low. to me something wrong there. I don't know how Naushad OKayed it.
2) Koi pyar ki dekhe from kohinoor ----- lata sings mukhda with breath and rafi take breath. The mukhda I ccan sing without breath and as per rafi he has sang longer lines without breath. Cannot be excepted as shotcoming in rafi but Naushad okayed it. listening to that song you feel odd when both lata and rafi sing togather and one breaking for breatch while other doesn't.
3) Yeh dil diwana hai from isqt par jor nahin----- again the breath taken by rafi and not by lata even when singing togather the same lines.
4) dost dost na raha from sangam ---- mukesh completely goes offbeat at one instant while ending mukhda with na raha.
5) aaye mere dost aye mere hamdam ----- ending was at very high note but song ends at HUM and leaves you standed in middle probably in movie someone puts hand on hero's mouth.
6)mere naina from mehbooba --- kishore started the songs at very low scale (although it appears very tough song to people who just hear kishore's song). Rafi would have sang it better. It was more of RD's ego to prove himself unique which costed the song to become better. Lata's version is far better. Kishore sing with false notes.